Electrical conductor



May 17, 1966 D. H. SCOFIELD ELECTRICAL CONDUCTOR Uriginal Filed July 2,1959 INVENTOR DONAL 0 H. 5 c OF/ELD BY w -fmwa ATTORNEYJ- United StatesPatent 26,024 ELECTRICAL CONDUCTOR Donald H. Scofield, Redwood City,Calif., assignor to Insul-8-Corp., San Carlos, Calif., a corporation ofCalifornia Original No. 3,060,260, dated Oct. 23, 1962, Ser. No.

824,630, July 2, 1959. Application for reissue Oct. 15,

1963, Ser. No. 316,800

2 Claims. (Cl. 174--117) Matter enclosed in heavy brackets appears inthe original patent but forms no part of this reissue specification;matter printed in italics indicates the additions made by reissue.

This invention relates broadly to electrical distribution systems fordelivering electrical energy to one or more electrically operateddevices located within an area to be served, and in which a principalconductor member is suspended within the area and may be tapped at anynumber of points along its length by connections to the various deviceswhich are to be operated. An important object of the invention has beento provide in such a system a cable-like electrical conductor which issuspended within the area to be served and which comprises not only theelectrical conductor means but also other means of high tensile strengthfor supporting the cable-like conductor in its suspended position.

A suspended electrical distribution system of the type provided by theinvention is constructed and intended to perform several functionsusually accomplished by more elaborate mechanical and electricalsystems. The suspended cable of such a system comprises a centralmechanical load carrying member and additional current carryingconductors and is constructed and intended to be strung across largeopen areas in industrial installations, where it is principallysupported by the central load carrying member and to a lesser degree, ifat all, by supports spaced along its length. In cables of the type towhich the invention relates, the load carrying member and the currentcarrying conductors are elongated and are embedded, in spaced parallelrelation to each other, in electically insulating material, with theconductors closely adjacent the surface of the body of insulatingmaterial so that they may be engaged by contact members which eitherpierce the insulating material or extend through openings therein.

In typical cables of the type to which the invention relates the loadcarrying member is positioned in the center of the cross section and thecurrent conductors are positioned equidistantly on either side of it orsymmetrically about it. It will be apparent that the positions of theconductors must be known and must remain the same with respect to eachother in order that the same phase relation will exist throughout thelength of the cable and with respect to its two sides. For example, in atwo-phase system in which the central supporting cable is grounded andthe voltages across the two conductors are of opposite phase, anytwisting of the main cable through 180 about its axis will cause the twoconductors to lie on the opposite sides of the cable from the positionswhich they normally and properly occupy. The resultant cross-phasing orreverse phasing, unless corrected by reversal of the take-0t? contacts,would render the electrical distribution system ineffective to operatethe devices which it is intended to energize.

It is, accordingly, the principal object of this invention to provide acable for an electrical distribution system of the described type whichis so constructed that twisting of the cable, with consequent reversephasing of the conductors, is prevented and substantially eliminated.

The invention is described in the following specification and isillustrated in the accompanying drawing, in which:

FIG. 1 is a perspective view showing a cable of known Reissued May 17,1966 construction of the general type to which the invention relates,twisted in the manner prevented and substantially eliminated by thisinvention.

FIG. 2 is a perspective view of a cable constructed in accordance withthe invention, with parts removed, and

FIG. 3 is a view similar to FIG. 2 but showing the supporting cable andthe conductors of the cable with the insulation removed therefrom andwith parts of the strands displaced to better illustrate the invention.

In FIG. 1 of the drawings there is shown a conductor cable A of knownconstruction and of the general type to which the invention relates andwhich comprises an elongated cable-like body 2 formed of electricallyinsulating material in which there is embedded a stranded wire cable 4formed of a plurality of helical wire strands all of which have the samedirection of lay. This stranded cable is positioned centrally of thegenerally rectangular cross section of the cable and extendssubstantially from end to end thereof. Positioned on opposite sides ofthe cross section of the body of cable 2 and in the disclosed structurebut not necessarily embedded in the body 2 are elongated conductor wires6, 8 which are, respectively, positioned adjacent opposite side walls oredges of the body 2 where they may be engaged by pointed contact members(not shown) which pierce the adjacent parts of the body 2 or extendthrough openings therein.

In the use and operation of a known conductor cable such as isillustrated in FIG. 1, the ends of the stranded cable 4 are connected tofixed, spaced supports. such as the opposite walls of a room, and thecable is drawn tight between these supports to cause the conductor cableA to be brought to substantially horizontal position supporting thetake-off devices and leads connected to it.

It has been found that if the stranded wire rope or cable 4 is formed ofstrands having the same direction of lay, as in FIG. 1, the entireconductor cable will be turned or twisted about its axis when the endsof the stranded cable are pulled in order to bring the conductor cableinto substantially horizontal position. This effect is illustrated inFIG. 1 of the drawing and it will be seen from this figure that thepositions of the electric wires 6, 8 are reversed because of thetwisting of the cable due to the tensioning of the uni-directionallylayed strands of the wire rope or cable 4. This reversal of thepositions of the conductors 6, 8 can render the entire electricaldistribution system inoperative, it being remembered that theseconductors are to be engaged by contact members which are connected tothe terminals of an electrical device which is to be energized. It willbe apparent that if the electrical device is to be supplied withtwo-phase energy the contacts which are connected to the terminals ofthe electricaldevice must engage the wire conductors 6, 8 in a properand pre-determined relation in order to supply electrical energy to theelectrical device in a pre-determined phase realtionship. If theconductor cable is twisted about its axis in the manner illustrated inFIG. 1, the phase relations of the voltages in the conductors 6, 8 willbe reversed and the electrical device connected to the contacts whichengage these conductor wires will be supplied with improperly phasedelectrical energy and will not be operated.

My invention provides an electrical conductor cable of the general typeillustrated in FIG. 1 but so constructed that it will not twist aboutits axis when the central supporting cable is placed under tension inbringing the conductor cable to the substantially horizontal position inwhich it is usually positioned in operation. A cable having theconstruction provided by the invention is disclosed in FIGS. 2 and 3 andcomprises an elongated, cable-like body 20 formed of electricallyinsulating material and which may be manufactured by a molding orextrusion sectional shape throughout its length. This cable-like processor the like and which may have any desired crossbody has embedded in itand extending substantially throughout its length two spaced conductorwires 22, 24 which are adapted, as with other cables of this type, to beengaged by contact members connected to the terminals of a device, toolor the like which is to be energized, and which contacts either piercethe insulating material of which the cable 20 is formed or extendthrough openings in the insulating material. The conductor cable 26 alsohas embedded therein and extending substantially throughout its length acable, rope or the like 26 which not only provides the sole means forsupporting the entire distributor cable, but also is connected to groundso that it may provide a ground terminal for the energizing circuits forthe electrical devices which are to be operated.

In accordance with the invention the cable 26 is formed of strandedconstruction and comprises at least two layers of strands which arelayed in opposite directions. Thus, as shown in FIGS. 2 and 3 of thedrawings, the cable, which is indicated generally at 26, comprises aninner layer 28 formed of helical strands layed in one direction and anouter layer 30 of helical strands layed in the opposite direction. Inthe embodiment of the invention disclosed in FIGS. 2 and 3 of thedrawings there is also provided a central or inner core or rod 32 whichis positioned within the inner layer 28 and which may be formed of aplastic or other suitable light-weight, bendable material. It will beunderstood that this interior member 32 may be omitted entirely withoutdeparting in any way from the invention, the principal feature of whichis the provision of an embedded cable formed of layers ofoppositelylayed strands and which is provided for the purpose ofsupporting the entire conductor cable and acting as the ground for theelectrical circuit including the conductor wires. These layers ofoppositely-layed strands prevent any twisting of the cable 26 about itsown axis when the cable is placed under tension in supporting the entireconductor cable, for the reason that the tension applied to the strandsof the two layers will cause equal and opposite forces to be set up inthe cable 26 acting in opposite directions about the axis thereof. Theseforces will cancel each other and prevent any twisting of the cableabout its own axis, in this way preventing the effect illustrated inFIG. I and causing a cable constructed in accordance with the inventionto be maintained and held always in untwisted condition, thus preventingreversal of the positions of the spaced conductors 6, 8.

While I have described and illustrated certain forms which my inventionmay take, it will be understood that other embodiments, as well asmodifications of those disclosed, may be made and practiced withoutdeparting in any way from the spirit or scope of the invention, for thelimits of which reference must be made to the appended claims.

What is claimed is:

I. In on [An] electrical cable-like conductor device constructed andintended to be suspended across large open areas, said cable-likeconductor device maintaining the same phase relation throughout itslength so that contact members may engage any point of said device andbe supplied with properly phased electrical energy; [for engagement bycontact members, comprising] an elongated unitary cable-like body formedof electrically non-conductive material, said body at each cross-sectionthroughout its length having a central part of maximum thickness andoppositely extending side parts, each of said side parts being definedby upper and lower walls which converge outwardly from the central part,an elongated cable-like supporting and grounding member of substantialstrength embedded within said central part and extending substantiallythroughout the length of the elongated body, said supporting membercomprising an inner member [of circular cross section] surrounded by asingle layer of solid strands helically wound around the inner member inclose engagement with said inner member and with each other and a secondlayer of solid strands helically wound around said first layer ofstrands in close engagement with each other and with said first layer,the strands of each of said concentric layers being laid in a directionopposite to that of the strands of the adjacent layer to preventtwisting of said elongated cable-like supporting and grounding membcrabout its own axis when said member is placed under tension, and anelongated electrically conductive member positioned within each of saidside parts on opposite sides of said supporting member and extendingsubstantially throughout the length of the cable-like body and adaptedto be engaged by electrical contact members extending through thenon-conductive material of the cable-like body, said non-twistingsupporting member maintaining a predetermined phase relationship betweensaid conductive members throughout the length of said cable-like body.

2. In an electrical cable-like conductor device constructed and intendedto be suspended across large open areas, said cable-like devicemaintaining the same phase relation throughout its length so thatcontact members may engage any point of said device and be supplied withproperly phased electrical energy, an elongated unitary cable-like bodyformed of solid electrically non-conductive material having a uniform,non-circular, cross-sectional configuration; means for supporting saidcable-like body including a supporting and grounding cable ofsubstantial strength solidly embedded within said solid electricallynon-conductive material and extending substantially throughout thelength of the elongated body, said supporting and grounding cableincluding means for producing equal forces acting in opposite directionsabout the cable axis when the cable is placed under tension to preventtwisting of the cable about its own axis when the cable supports saidcable-like body, and at least two elongated, electrically conductivemembers solidly enzbcddcd within said solid, electrically non-conductivematerial in fixed parallel spaced relation to one another, to saidcable, and to the non-circular exterior of the insulation material, saidconductive members extending substantially throughout the length of thecable-like body and adapted to be engaged at any point of saidcable-like body by electrical contact members extending through thenon-conductive material of the cable-like body, said non-twisting cablemaintaining a predetermined phase relationship between said conductivemembers throughout the length of said cable-like body.

References Cited by the Examiner The following references, cited by theExaminer, are of record in the patented file of this patent or theoriginal patent.

UNITED STATES PATENTS 1,201,290 10/1916 Harrison 174-108 1,904,1144/1933 Baum l74128 1,950,858 3/1934 Metcalf 57149 2,261,986 11/1941Frank et al 339-23 2,463,590 3/1949 Arutunolf l74-l08 2,589,507 3/1952Noyes 174l08 2,779,149 1/1957 Schuller 57-148 2,950,338 8/1960 Taylor17440 FOREIGN PATENTS 834,353 5/1938 France.

12,835 1849 Great Britain. 424,995 9/1947 Italy.

LARAMlE E. ASKIN, Primary Examiner.

E. JAMES SAX, BENNETT G. MILLER, JOHN P.

WI LDM AN, Examincrs.

S, SACKS, K. R, PETERSON, Ass/stunt Ernnu'ncrs.

